How Do You Fix Wifi Issues
Understanding Internet Addressing
When you are connected to the Internet, you will receive either a Public IPv4 address such as 171.46.10.110 or an IPv6 address like 2000:bbb3:22b8:95fb:f611:c845:2c43:37f6. These addresses can be verified at https://test-ipv6.com/. However, conveying these addresses or even MAC addresses like b2:ca:98:fb:61:33 to people who are not tech-savvy can be prone to error and can become complicated rapidly. Furthermore, this method does not provide any historical data, particularly for past issues.
Navigating the World Wide Web
When trying to access a website such as https://auer.info, the first step is to connect to a DNS server to convert the host portion (auer) combined with the Top Level Domain (info) of the URL into an IP address like 64.85.232.250. In every web request, your computer and browser send their types, such as Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16.
Significance of Default Gateways
The default gateway is typically an automatically configured address through DHCP. You will receive a default gateway like 192.168.14.221 (although they typically end in .1 or .254 depending on the scope size), and this is where your computer forwards all of its traffic to be routed further. For IPv6, you can find detailed information on how-to-fix-ipv6-connectivity/, or alternatively, you can check on Mac or Linux using the following command:
IPv4 Routes and the Host IPv4 Route Table (inc. VPN)
netstat -rn -f inet | egrep -i "default|0/1|128.0/1"
0/1 172.18.12.193 UGScg utun3 default 192.168.14.221 UGScg en0 128.0/1 172.18.12.193 UGSc utun3
Note: We are not just looking for the default but also for any VPN that overrides the public v4 address space.
IPv6 Routes and the Host IPv6 Route Table (inc. VPN)
netstat -rn -f inet6 | egrep -i "default|2000::/3"
If you have IPv6 active the above should return at least one route (as per below) via a known interface such as “en0 " on a Mac.
default fe80:f3e9:ad6e:7f08:4572%en0 UGcg en0 default fe80::%utun0 UGcIg utun0 default fe80::%utun1 UGcIg utun1 default fe80::%utun2 UGcIg utun2 2000::/3 utun3 USc utun3
Note: We are not just looking for the default but also for any VPN that overrides the public v6 address space.
Debugging DHCP for both IPv4 and IPv6
To get a look at the low level DHCP configuration (Mac/Linux):
ipconfig getpacket en0
...
domain_name_server (ip_mult): {150.243.35.44, 112.47.36.15}
end (none):
...
So, in the above we are not getting IPv6 DNS servers from the DHCPv4 reply but…
ipconfig getv6packet en0
DHCPv6 REPLY (7) Transaction ID 0x80940b Length 76
Options[4] = {
CLIENTID (1) Length 14: DUID LLT HW 1 Time 668691856 Addr b2:ca:98:fb:61:33
DNS_SERVERS (23) Length 32: 2606:4700:4700::1111, 2001:4860:4860::8844
DOMAIN_LIST (24) Length 0: Invalid
SERVERID (2) Length 10: DUID LL HW 1 Addr a7:7d:10:76:62:26
}
Resolve Wired and Wireless Connectivity Issues
When trying to transfer data to your router, you may encounter issues at the physical and data layer, whether you are using a wired or wireless (Wi-Fi) medium.
Troubleshooting Tips for Apple macOS / OSX
Regardless of whether you are running OSX or macOS version 10.14.3, 11.4.9, or 12.2.5, there are various troubleshooting tools available. However, these manual actions and scripts do not provide a series of correlated values over time. For this reason, automated remote troubleshooting is particularly valuable for teams that have embraced remote work and Work From Anywhere (WFA).
Useful Built-in Scripts
One useful tool on OSX/macOS is sudo wdutil info, which provides a dump of current wireless settings to the CLI, and can be configured to generate specific logs for troubleshooting. Moreover, the sysdiagnose tool is even more comprehensive, generating a wide range of logs (though much is only related to wireless at a specific point in time, similar to wdutil).
To run it in the background and write logs to /var/tmp/<blah>.tar.gz, use the command sudo nohup /usr/bin/sysdiagnose -u &. If you prefer to run it interactively, you can do so by entering sudo /usr/bin/sysdiagnose in the terminal. Keep in mind that the file sizes are approximately 300MB.
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